<form id="frmLang" action="<?php echo url_for('@changeLang') ?>" method="post">
  <input type="hidden" name="uri" value="<?php echo $sf_request->getUri() ?>" />
<select name="lang" onchange="submit('frmLang')" style="width: 100px;background-color: #F6F6EA;border: 1px solid #CDD2D6;">
  <option value="en" <?php if($sf_user->getCulture()=='en'){echo 'selected';} ?>>Inglés</option>
  <option value="es" <?php if($sf_user->getCulture()=='es'){echo 'selected';} ?>>Español</option>
</select>
</form>